Abstract <p>Critical bone defects pose significant challenges to effective treatment. However, drug loading within scaffold structures has emerged as an advanced strategy for successful bone tissue regeneration.</p> Purpose <p>This study investigates the effects of nano-zinc oxide (nZnO) and metformin (MET) on angiogenesis and osteogenesis in electrospun scaffolds under both in vitro and in vivo conditions.</p> Methods <p>Electrospun scaffolds, composed of poly(ε-caprolactone), nano-hydroxyapatite, and nZnO, were ultrasonicated to modify pore sizes and enhance bone regeneration. Subsequently, gelatin nanoparticles containing metformin (MET/GNPs) were covalently bonded to the scaffolds. MET/GNP-loaded scaffolds were co-cultured with human umbilical vein endothelial cells and rat bone marrow mesenchymal stem cells. In vitro assays, including MTT, ALP, and alizarin red staining, were performed to assess cytotoxicity, differentiation, and mineralization, respectively. Angiogenesis and osteogenesis were further evaluated in vivo using a rat calvarial defect model through CT imaging, hematoxylin and eosin staining, Masson’s trichrome staining, and immunohistochemistry (IHC).</p> Results <p>Scanning electron microscopy revealed nano-scale dimensions of the fibers and nanoparticles, while dynamic light scattering confirmed nanoparticle properties. The loading content and loading efficiency of MET/GNPs were calculated as 56.4% and 12.5%, respectively. Results demonstrated significantly enhanced cell viability in MET/GNP-loaded scaffolds, along with increased ALP activity and mineralization capacity. Histological and IHC analyses confirmed successful stimulation of angiogenesis and osteogenesis in vivo.</p> Conclusion <p>These scaffolds show significant potential for promoting osteogenesis and angiogenesis in bone tissue engineering.</p>